Off-peak water heating system



Dec. 16, 194 c. OSTERHELD 2,266,247

INVENTOR CLARk OSTERHELD ATTO RNEY Patented Dec. 16, 1941 I 2,266,247OFF-PEAK WATER HEATING SYSTEM Clark M. Osterheld, Stoughton, Wis.,assignor to McGraw Electric Company, ,Elgln, 11]., a corporation oiDelaware Application November 7, 1940, Serial No. 364,639

Claims.

My invention relates to electric water heating systems and particularlyto off-peak water heating systems, particularly applicable for domestichot water tanks,

An object of my invention is to provide a relatively simple heaterenergization delaying means subject to time and to tank watertemperature for causing a predetermined delay in the energization of theheater at the start of an off-peak period in case a predetermined part01' the water content of the tank is hot.

Another object of my invention is to provide a heater energization delayswitch which is opened by electromagnetic means and permitted to returnslowly to closed position, the delay being eflected by a suitable delaygear train.

Other objects of my invention will either be apparent from a descriptionof one form of system now preferred by me or will be pointed out in thecourse of such description and set forth in the appended claims.

In the single sheet of drawings,

Figure 1 is a diagram of connections of my improved system as applied toan ordinary domestic hot water tank, and,

Fig. 2 is a generalized view, in an auxiliary control switch.

In the case where public utilities provide electric current of adistrict, particularly an urban side elevation, of

district, it is usually desired by the operators to provide a load forthe supply circuit or distribution system that shall be connectedthereto at the time of reduced total load connected to the system. Wherea lighting load constitutes a relatively largepart oi the total load, itis evident that this total load will be a minimum during the later hoursof the night, say, approximately, from 1 o'clock to 5 o'clock or so inthe morning.

The ordinary oil-peak water heating system which starts energization ofthe electric hot water tank heaters at the start 01' the oil-peakperiod, which may be at :00 p. m. or 11:00 p. m., means that the heaterwill be disconnected upon all 01' the water in the tank being hot at anearly hour in the night, say 2 o'clock or 3 oclock, so that covered witha mass ll of heat insulating material which, for protective purposes,may be encased by an outer casing i9. All of these elements are old andwell known in the art and variations may be made therein withoutdeparting from the spirit and scope of my invention since they form nopart of the present invention.

I provide an electric heater 2| for the tank which heater may be ofgenerally annular shape and extend peripherally around the tank near thelower end thereof, being positioned in a tunnel 23. Reference may herebe made to my Patent #2,226,526 issued December 24, 1940, whichdiscloses and claims a tank heating element which I may use in thissystem.

I provide a main thermally actuable switch 25 responsive to thetemperature 01 the water in the tank near the lower part thereof. Thisswitch includes a tubular member 21 which is secured to the wall of thetank I I in a fluid-tight manner to be positioned within the tank. Itincludes also an expansion rod 29 adapted to'engage with a resilientcontact arm ll normally yieldingly biased out of engagement with arelatively rigid contact arm 33 but adapted to be moved out 01'engagement therewith when expansion rod 29 has been expanded by reasonof the subjection of tubular member 21 to the high temperature of hotwater. While I have shown a specific position or the heater 2| and ofthe thermally actuable switch 25, I do not desire to be limited thereto,the only object being to ensure that thermal switch 25 will not eiTectdisengagement 01' contact arms 3i and 33 until substantially all of thewater in the tank is hot.

I provide also a continuously operative timer or timing means 3! whichincludes a continuously operable electric synchronous motor 31.

which is electrically connected with supply circuit conductors l9 and Iwhich are to be considered as being energized continuously. A worm gear43 is operated by the motor 31, this gear engaging a worm wheel 45, thispower drive being so designed, constructed and adjusted that the wormwheel ll makes one revolution in twentythe water heater load will not bepresent and four hours.

connected to the system at the time or the oc- A worm wheel 48 ismounted on a shalt 41 currence of the most pronounced dip or valley inwhich shaft has also mounted thereon a cam disc the load curve. 49, thegreater part 01 the periphery of which is A hot water tank H isillustrated as being of the elongated cylindrical type usually used indomestic hot water installations and may be provided with a cold waterinlet pipe I! connected therewith at the bottom, I! connected therewithan outlet hot water pipe at the top and may be of uniform outer radiusbut which has a peripheral portion ll thereon of somewhat greater outerradius. The peripheral extent of the part II is that corresponding tothe desired length of oil-peak period and, for purposes or illustration,is here shown as being of substantially onethird the total periphery,that is, the-length of oil-peak period is substantially eight hours. Ifit be further assumed that the operators of the power station supplyingcurrent to this system consider that the start of an off-peak periodshould be at :00 p. m., it is evident that the end of the off-peakperiod will be at substantially'6:00 a. 111.

While I have hereinbefore set forth that the worm wheel 45 and thereforethe shaft 41 should rotate through one complete revolution intwenty-four hours, it is obvious that speed-reducing gear wheels notshown in the drawing may be provided to cause only the cam disc 49 torotate once in twenty-four hours. It is, therefore, to be understoodthat the showing of the continuously operative timer 35 is mainly for illustrative purposes and I may use any other form of continuouslyoperative timer effective for the same general purpose.

I provide a main timer-controlled heater switch 5| which includes arelatively rigid 'contact arm 53, and a resilient contact arm-55,normally yieldingly biased out of engagement with contact arm 53 butadapted to be moved into engagement therewith when the leading end ofpart 5| of the cam disc 49 engages a lug 51,

,preferably made of electric insulating material,

which is mounted on the arm 55 near its outer end. I provide further aheater-energization delay means including a pair of fixed contactmembers 59, a contact bridging member 6| which is insulatedly mounted ona lever arm or bar 53 which is tumably mounted on a shaft 65 of a del ygear train 61, the operation of which will be set forth in due course. Iprovide further a fixed electromagnetic coil 69 which is adapted tomagnetically energize a movable core member 1| which is connected by alink 13 to the arm 53, in a pivotal manner.

The delay gear train mechanism is shown schematically or generally onlysince I may use any of the several devices of this kind now on themarket or shown in earlier patents, and I will, therefore, describe onlythe operation thereof as applied to my improved water heating system. Itis desired, under certain operating conditions, to energize the coil 69with resultant quick upward movement of core 1| into an upper positionin which the lever arm 63 will occupy the position shown by the brokenlines and at which time the contact bridging member 6| will be out ofengagement with the fixed contact members 59. Any suitable or desiredstop means may be provided to limit the counter-clockwise turningmovement of arm 53 and I have therefore shown a stop pin 15 although anyother means effective for the same purpose may be employed.

After arm 53 has been moved to its upward position, as hereinbeforedescribed, it is to be permitted to return slowly to the normal, closedposition, as shown by the full lines in Fig. 1 of the drawing, and thetime required for such return is fixed by the adjustable delay geartrain which may be of anysuitable or desired kind in- V on a contactmember switch for coil 69, including a down period within certaingeneral limits so that I can obtain a delay of say two hours or of threehours by movement of an adjusting arm 11, all in a manner well known inthe art.

The supply circuit conductor 39 is connected to contact arm 55 by aconductor 19 and the contact arm 53 of switch 5| is connected to one ofthe fixed contact members 59 by a conductor 8|. The other fixed contactmember 59 is connected by a conductor 83 to one terminal of the heater2|, while the other terminal thereof is connected by a conductor 85 tocontact arm 33. The'other contact arm 3| of the main terminal switch 25is connected by a conductor 81 to the other supply circuit conductor II.

I provide an auxiliary thermally actuable switch 89 responsive totankwater temperature in an upper part of the tank and this switchincludes a tubular member 9|, an expansion rod 93, a relatively rigidcontact arm 95 and a resilient contact arm 91 normally yieldingly biasedout of engagement with contact arm 95 but moved into engagementtherewith when tubular member 9| and expansion rod 93 are subject to therelatively high temperature of hot water.

I provide further an auxiliary circuit-controlling means for coil 59which I have shown generally in Fig. 2 of the drawing as including asupport 99, of channel shape, which has slidably movable therein apreferably vertically extending rod IN. This rod has mounted there- I03adapted to be moved into and out of engagement with a fixed contactmember I05. The rod |0| has also mounted thereon a flat member I01 whichis spaced a suitable distance from the contact member I03 for a purposewhich will presently appear.

I provide also a second circuit-controlling pair of normally disengagedcontact arms I09 and III adapted to be moved into engagement with eachother at the start of an off-peak period by a short cam I face II3, theperipheral extent of which may be on the order of say five or tenminutes. The exact time-extent of cam surface I I3 is relativelyimmaterial so long as its time-extent is less than the shortest possibletime providable by the delay gear train I51.

Conductor BI is connected to one terminal of coil 99 by a conductor I|5while the other terminal of coil 69 is connected by a conductor 1 withthe movable contact member I03. The fixed contact member I05 isconnected by a conductor II9 with contact arm. I09. Contact arm III isconnected by a conductor |2| with contact arm'95 of the auxiliarythermal switch 89 and contact arm 91 is connected by a conductor I25with contact arm 33 of th main thermal switch.

Let it be assumed that at 10:00 p. m. the continuously operativetimer'has moved the camdisc 49 to the position shown inFig. l of thedrawing to thereby cause engagement of' contact arms 55 and 53 andalsoof contact arms I09 eluding an escapement to cause slow rundown V ofthe gear train as driven by the lever 53 having connected therewiththecontact bridging member 6| and the core member II and an additionalweight if necessary. I may, of course, use a spring-driven gear trainwhich is wound up by the counter-clockwise turning movement of lever arm53 and I prefer to use a delay gear train structure which will permit ofvarying the runand III. Before such engagement was efiected,

the lever arm 63 and the parts secured thereto were in the positionshown in the full lines in Fig. 1 of the drawing so that contact memberI03 on the movable rod MI was in engagement with fixed contact memberI05 whereby an energizing circuit through coil 59 was provided as soonas arms-I09 and III were engaged with each other and in case the upperauxiliary thermal switch 89 was subject to the temperature of hot waterin the tank with attendant engagement of con- I closing or such heatercircuit after tact arms 97 and 95. This energizing circuit is asfollows: From supply circuit conductor 39, through conductor I9, throughengaged contact arms 55 and 53, through conductors 8I and I I5, throughcoil 69, through conductor 1, through engaged contact members I03 andI05, through conductor II9 through engaged contact arms I09 and III,conductor I2I through engaged contact arms 91 and 95, through conductorI25, through engaged contact arms 33 and 3I and from there throughconductor 81 to the other supply circuit conductor 4|. This will resultin a quick upward movement oi core member 1| and attendant quick turningmovement, in a counterclockwise direction, of lever arm 63 and thedistance between members I03 and I! is such that when lever arm 63 hasreached substantially its upper position, as shown by the broken linesin Fig. 1 of the drawing, the left-hand end of lever arm 63 will engagemember I01 to efiect slight downward movement of rod IOI anddisengagement of contact member I03 from contact member I05. This willresult in deenergizing the coil 69 and, as hereinbefore set forth, willnow permit slow return movement of lever arm 63 in a clockwisedirection, this arm reaching the position shown in the full lines inFig. 1 of the drawing after a predetermined delay period which, forillustrative purposes, may be assumed to be two hours. It is thereforeevident that at say approximately 12:00 p. m., a heater circuit throughthe heater II will be closed as follows: From supply circuit conductor39, through conductor '19, through the engaged contact arms 55 and 53,through conductor8I, through the engaged contact members 59 and 6I,through conductor 93 and heater 2I, through engaged contact arms 33 and3| and from there through conductor 81 to the other supply circuitconductor II.

It is, therefore, evident that in case a predetermined fractional partof the .water content in the tank is hot at the start of an oiI-peakperiod, with attendant subjection of the upper thermal switch 09 to hotwater, an energizing circuit through the electromagnetic coil 69 isprovided resulting in opening of the heater energizing circuit Justabove described with delayed a length of time adiustable by the operatoror the user of such a system.

The auxiliary timer-controlled switch including the contact arms I09 andIII will have been moved to open position within a short time after thestart of an off-peak period, so that when lever arm 63 has moved intothe position shown in the full lines with attendant engagement ofcontacts I03 and I05, the energizing circuit of coil 69 will not beclosed so that energization of the heater II can continue until all ofthe water is hot or until the end of the oil-peak period It-is furtherobvious that in case the upper auxiliary thermal switch 69 was subjectedto the temperature of cold water at the start of an ofipeak period whencontact arms 65 and 53 were moved into engagement with each other, thatthe above described energizing circuit of coil 69 would not be provided(since contact arms 95 and 91 would be disengaged from each other) andcontact bridging member 6| would be and remain in engagement with, thefixed contact members 59 to effect immediate energization of the'heater.It is therefore evident that the electromagnetically operable delayheater control means, including more particularly the contact 3 6I aswell as the other elements operatively associated therewith, areeffective to cause energization of the heater at a time varying inaccordance with the amount of cold water in the tank. That is, if morethan a predetermined amount of cold water is in the tank at the start ofan oil'- peak period, the heater will be energized at the start of sucha period but if less than such an amount of cold water is present in thetank, energization of the heaterwill be delayed for an adjustably presetfixed length of time.

It is, therefore, obvious that my improved system provides means tendingto have-the energization of a tank water heater occur during the morepronounced dip or valley usually occurring in a load curve during thelater hours of the night, that is, from say 2:00 a m. to 5:00 or 6:00 a.m.

Various modifications may be made in the system embodying my inventionas herein shown and described and all such modifications clearly comingwithin the scope of the appended claims are to be considered as beingcovered thereby.

I claim as my invention:

1. An oiT-peak water heating system for a tank having an electricheater, comprising a continuously operative timer, a normally-openmainheater-control switch adapted to be moved into i and held in closedposition by the timer during members 59 and the contact bridging memberan off-peak period, an electromagneticallyactuable normally-closedheater-control switch controlled in accordance with time and tank watertemperature at an intermediate point in the tank to selectively causeopening of said normally closed heater control switch for apredetermined fixed length of time at the time of closure of said mainswitch by the timer at the start ofan off-peak period in cases.predetermined fractional part of the water content of the tank is hotand to cause said switch to remain closed in case less than saidpredetermined fractional part of the water content is hot.

2. An oiI-peak water heating system for a hot water tank having anelectric heater, comprising a main normally-open heater-control switchadapted to be held closed during an off-peak period of predeterminedlength, a second normally-closed heater-control switch in serieselectric circuit with said main switch, time and tank water temperaturecontrolled means for selectively causing opening of said'second heatercontrol switch at the start of an ofl-peak period in case apredetermined fractional part of the water content of the tank is hotand reclosing of said second switch after a preset fixed delay periodand causing said second switch to remain closed in case a predeterminedfractional part" 01' the water content of the tank is cold.

3. An oil-peak water heating system for a hot water tank having anelectric heater, comprising a tank water temperature responsiveheatercontrol switch movable to open position when substantially all ofthe water in the tank is hot, a normally-open heater-control switch, acontinuously operative timer adapted to move the normally open heatercontrol switch into and hold it in closed position during an oflf-peakperiod only, an auxiliary switch adapted to be moved into closedposition momentarily by the timer at the start of an ofi-peak period, anormally-closed heater-energization delay switch series circuit withsaid an auxiliary tank water switch, electromagnetic by said auxiliarytimerelectrically connected in heater-control switches, temperaturecontrolled means controlled Jointly controlled switch and said auxiliarytemperature controlled switch to selectively cause opening of saidnormally-closed heater energizing switch at the start of an off-peakperiod for an adjustably preset "length of time in case a predeterminedY fractional part of the water content of the tank is hot and to causesaid 1 to remain in closed position in case less than saidnormally-closed switch predetermined fractional part of the watercontent of the tank, isvhot,'heater deenergization being efiectedselectively by the tank water temperatureresponsive heater-controlswitch in case substantially all ofthe water in the tank is hot beforethe-end of an ofi-peak-period and by the normally-open timer-actuatedheater-control switch at the end of an ofi-peak period in case lessthanthe full water content of the tank is hot at the end of an oil-peakperiod. I 4. An ofi-peak water heating system for a tank having anelectric heater, comprising a continuously operative timer, a normallyopen main heater control switch adapted to be moved into and be held inclosed position by the timer during an off-peak period, a normallyclosed heater control switch, an electromagnet for causing opening ofsaid normally closed switch, means for causing energization of saidelectromagnet comprising a thermal switch subject to tank watertemperature at an upper point of the tank Y anda normally open switchadapted to be closed momentarily by the timer at the start of anoil-peak period, energization of the electromagnet and opening of saidnormally closed heater switch being effected at the start of an off-peakperiod in case the thermal switch is subject to cold water and means formaintaining said normally closed heater control switch in open positionfor an adiustably preset time inter va 5. An ofl-peak water heatingsystem for a tank having an electric heater, comprising acontinuouslyoperative timer, a normally open heater 7 control switch adapted to bemoved into and held in closed position by the timer during an of!- peakperiod, a normally closed heater control switch in series electriccircuit with said timercontrolled heater control switch, an auxiliaryswitch adapted to be moved momentarily into closed position by the timerat the start of an ofl-peak period, a thermal switch subject to tankwater temperature, electromagnetic means .con-

trolled jointly by said auxiliary timer-controlled switch and saidthermal switch for causing opening of said normally closedheater-control switch for a preset fixed time interval in case saidthermal switch is subject to hot water and for preventing opening ofsaid normally closed heater control switch in case said thermal switchis subject to cold water.

CLARK M. OSTERHELD.

